1. Field of the Invention
The present invention relates to a profile generating apparatus, a profile generating method, a computer-readable recording medium with a profile generating program recorded therein, and a printing system, which are capable of generating a profile for color matching depending on optical characteristics of a protective-film-covered print that carries a color image printed on a print, and which is covered with a protective film.
2. Description of the Related Art
With significant advances in inkjet technology in recent years, it has been become possible for inkjet printers to produce large color prints of high quality at high speeds. Inkjet printers are not only popular for private or home use, but also are widely used in commercial applications nowadays. Inkjet printers make it possible to print on POP (Point Of Purchase) posters, wall posters, large-size mediums such as outdoor advertisements and billboards, roll mediums, and thick hard mediums.
There are a wide variety of print mediums (hereinafter also referred to as “mediums”) available for use in prints in order to meet various commercial demands. For example, such print mediums include paper mediums including synthetic paper, thick paper, aluminum-evaporated paper, etc., resin mediums made of vinyl chloride, PET, etc., and tarpaulin paper made of a woven fiber cloth with synthetic resin films applied to both surfaces thereof.
Since advertisement prints are expected to be effective in arousing consumers' motivation to buy advertised products through visual sensation, the finish of colors of the prints is of particular importance. Heretofore, there have been disclosed various color matching technologies, such as a method of generating an ICC (International Color Consortium) profile, a method of adjusting a designated color, etc., as print color managing means.
Advertisement prints are displayed in a variety of places including outdoor areas, indoor areas, and spotlighted exhibition sites. Generally, the spectral characteristics (spectral energy distribution) of environmental light as an observational light source for prints vary depending on different places where the prints are displayed.
Prints are broadly classified as transmissive images using a transmissive light source as a main light source, and as reflective images using a reflective light source as a main light source. Examples of transmissive light sources (i.e., backlighting) include fluorescent lamps such as F2, F6, F7 light sources, LEDs (Light Emitting Diodes), and organic EL (Electro-Luminescence) light sources, etc.
If different observational light sources are used for a print, then since the spectral characteristics of light emitted from different observational light sources and which finally reach the retina of human observers are different, the appearance (color impression) of the print, which is visually perceived by the observer, tends to vary depending on such observational light sources, although the tendency may differ from observer to observer. As a consequence, if the observational environment in which a print is produced, i.e., the location where the printer is installed, and the observational environment in which the print is displayed differ greatly from each other, then the print may possibly fail to exhibit desired colors.
Japanese Laid-Open Patent Publication No. 2007-081586 discloses a method of and an apparatus for independently storing spectral data of a print and a plurality of light source spectral data. A profile appropriate for an observational light source is generated each time that the observational light source is set up. This publication states that the method and apparatus can generate profiles corresponding to respective different observational light sources for colorimetric measurement in a reduced number of man-hours, and can perform appropriate color management for prints depending on such observational light sources.
Prints produced by inkjet printers may not endure in severe environments because the images thereof are not highly durable, particularly in terms of abrasion resistance and toughness.
For example, in exhibition sites that are exposed to high intensity radiant light at all times, color images of displayed prints tend to become gradually discolored because the dyes included in the inks are gradually decomposed by chemical reactions. Also, in display modes where prints are applied to indoor floors, color images of the prints are likely to become damaged because the print surfaces become abraded by people walking on the floors.
Attempts have been made to increase the durability of print images in such applications by covering the image-formed surfaces of prints with protective films such as laminating films, which are functionally treated by the addition of an ultraviolet absorbent, or through an embossing process. A print thus processed will hereinafter be referred to as a “protective-film-covered print”.
However, the results of investigation and research conducted by the inventor of the present invention have indicated that, although the laminating film has high transmittance, the spectral transmittance thereof is not necessarily flat within a visible wavelength range, and hence the appearance of printed color images that are covered with the laminating film tends to vary to a non-negligible extent, depending on whether the print is covered with a laminating film or not. It also has been discovered that there are many types of commercially available laminating films, which exhibit different spectral transmittances.
In order to obtain a profile of a protective-film-covered print with the method and the apparatus disclosed in Japanese Laid-Open Patent Publication No. 2007-081586, various prints having various laminating films covering image-formed surfaces thereof (i.e., various protective-film-covered prints) have to be measured colorimetrically. However, if colors are to be strictly reproduced with respect to all combinations of laminating films and prints, then it becomes highly tedious and time-consuming to prepare such samples and to colorimetrically measure them. Further, if characteristics of the laminating films are ignored, then the appearance of printed color images through the laminating films varies, depending on the type of laminating film that is used.